Centimeters and Millimeters | Converting cm to mm and Converting mm to cm | Math with Mr. J

[Music] welcome to math with mr j [Music] in this video i'm going to cover how to convert between centimeters and millimeters so centimeters to millimeters and millimeters to centimeters now one thing to keep in mind one centimeter equals 10 millimeters we need this information in order to convert let's jump into number one where we have 6 centimeters equals how many millimeters well again each of those centimeters is going to be 10 millimeters so we have 10 millimeters 10 millimeters 10 millimeters six times in other words six times ten six times ten equals sixty so six centimeters equals sixty millimeters when we go from centimeters to millimeters we multiply by 10. let's move on to number two where we have 30 and 74 hundredths or 30.74 centimeters equals how many millimeters now this number is not as easy to work with as number one number one we were able to use mental math and do six times ten here we're going to need to multiply by 10 again because we're going from centimeters to millimeters when we multiply something by 10 we can actually make this really simple all we need to do is move the decimal one time to the right when we multiply something by 10 each digit of that number shifts one place to the left the value of the number increases by 10. in other words we multiplied by 10. so technically the digits shift and increase in value but let's make this simple and move the decimal in order to push all of our digits to the correct place so to speak so again move the decimal once to the right in order to multiply by 10. so let me rewrite 30 and 74 hundredths here and we will move this decimal once to the right and it's now going to go in between the 7 and the 4. so we get 307 and 4 10 or 307.4 millimeters there so 30.74 centimeters equals 307.4 millimeters let me go back up to number one and see if moving the decimal for that one will work as well just to show that this will work for any problem multiplying by 10 move that decimal once to the right so we have 6 and the decimal always comes after a whole number so decimal and let's move it once to the right and fill this gap with a zero so we get 60 that way as well so to recap when going from centimeters to millimeters multiply by 10 and we can do that by moving the decimal once to the right let's move on to number three where we have 90 millimeters equals how many centimeters well each group of 10 millimeters equals a centimeter so we need to see how many groups of 10 are in 90 in other words 90 divided by 10 well ninety divided by ten is nine ninety millimeters equals nine centimeters when we go from millimeters to centimeters we divide by ten let's move on to number four where we have 275 and eight tenths or 275.8 millimeters equals how many centimeters now this number is not as easy to work with as the 90 from number three in number three we were able to use mental math in order to divide by 10. for number four when we divide by 10 we shift each digit to the right one place this will give us 1 10 the value of our original number in other words we are dividing by 10. we can do this by moving the decimal once to the left so let me rewrite 275 and 8 tenths here so again we're dividing by 10 and we can make this simple by just moving the decimal once to the left and the decimal is now going to go in between the 7 and the 5. so we get 27 and 58 hundredths so 275.8 millimeters equals 27.58 centimeters so there you have it there's how you convert between centimeters and millimeters when we go from centimeters to millimeters we multiply by 10 and we can do that by moving the decimal once to the right when we go from millimeters to centimeters we divide by 10 and we can do that by moving the decimal once to the left i hope that helped thanks so much for watching until next time peace